Friends in Partial Differential Equations

This volume is dedicated to Nina Nikolaevna Uraltseva on the occasion of her 90th birthday. It collects contributions by her numerous colleagues and friends sharing with her research interests in linear and quasilinear elliptic and parabolic equations, degenerate and geometric equations, variational inequalities, and free boundary problems.

In brief, the topics covered include regularity for transmission systems, bifurcation of solitary waves, parabolic equations with Morrey lower-order coefficients, mesoscopic modeling of optimal transportation networks, Sobolev regularity in nonlinear elliptic problems, planar loops with prescribed curvature, interface behavior for the solutions of free boundary problems, a multi-phase Stefan problem, homogenization of nonlocal convolution-type operators, an obstacle-type problem for the $p$-Laplacian with the fractional gradient, scalar variational problems with maximal singular sets, bifurcations in the Lotka–Volterra competition model, and the Dirichlet-area minimisation problem. In addition, the volume contains a description of Uraltseva’s main contributions to mathematics and the mathematical community.